The film’s focus is the PPPL’s main experiment in the 1980s and 1990s, the Tokamak Fusion Test Reactor (TFTR). This device used magnetic fields to contain a plasma made of hydrogen isotopes which were heated to a temperature so high that their nuclei fuse together into a new molecule, generating energy as a byproduct. TFTR’s goal was to develop a process of generating more energy through the fusion than the amount of electricity required to power the reactor containing the plasma. By 1989, TFTR’s successes included achieving a then record-temperature of 200 million degrees Celsius and confirming existence of a so-called “bootstrap current” within plasmas.